Background This study aimed to reclassify a subset of poorly differentiated salivary gland carcinoma that do not conform to any entities of the current World Health Organization (WHO) classification into the category of undifferentiated carcinoma (UDC) because they lack specific histologic differentiation or immunophenotype. Methods: Cases of salivary gland carcinomas from Asan Medical Center (2002–2020) that did not fit any existing WHO classification criteria and were diagnosed as poorly differentiated carcinoma, high-grade carcinoma, or UDC, were retrospectively reviewed. Immunohistochemical (IHC) staining for p40, neuroendocrine markers, androgen receptor (AR), and gross cystic disease fluid protein 15 (GCDFP-15) and Epstein-Barr virus (EBV) in situ hybridization (ISH) were performed. Clinical data were collected from the electronic medical records. Results: Six salivary gland carcinomas did not align with any specific entities and lacked distinct differentiation. Two of six cases displayed lymphoepithelial carcinoma (LEC)-like morphology but were negative or showed negligible immunoreactivity for p40 and EBV ISH, distinguishing them from LEC of the salivary gland. Two cases showed strong AR positivity, suggesting a potential overlap with salivary duct carcinoma (SDC) but lacked classic SDC morphologies and GCDFP-15 expression. No cases expressed neuroendocrine markers. Conclusions: This study proposes reclassifying these poorly differentiated or high-grade salivary gland carcinomas as UDC based on their indeterminate differentiation and IHC profiles. This may lead to a clearer diagnostic category and enhance our understanding of these high-grade tumors.
Lymphoepithelial carcinoma, also known as malignant lymphoepithelial lesion or lymphoepithelioma, is a rare tumor in salivary glands. Lymphoepithelial carcinoma has a characteristic histological findings comprising irregularly-shaped nests of malignant epithelial cells within a lymphocyte-rich stroma, occasionally forming lymphoid follicles. We recently experienced a case of fine needle aspiration cytology(FNAC) of lymphoepithelial carcinoma of parotid gland in a 61-year-old male. The FNAC yielded a hypercellular smear of many irregular clusters of malignant epithelial cells in the background of lymphoid stroma.
Lymphoepithelial carcinoma is a rare subtype of undifferentiated carcinoma in the salivary gland. The incidence of lymphoepithelial carcinoma is about 0.4% among the patients with major salivary gland tumors. It has a racial preference; about 75% of the patients are of Mongolian ancestry. We report a case of lymphoepithelial carcinoma arising in the left parotid gland of a 52-year-old man. Grossly, the tumor was relatively well demarcated, gray-white, and solid. Microscopically, the irregular shaped syncytial tumor cell islands were evident within lymphoplasma cell-rich and desmoplastic stroma. The carcinoma cells had large vesicular nuclei and prominent nucleoli. The tumor invaded the surrounding salivary gland tissue. Epstein-Barr virus (EBV) was demonstrated by in situ hybridization for EBV-encoded RNA-1 (EBER-1) and polymerase chain reaction for EBV nuclear antigen-1 (EBNA-1).